[noun] [C] - any stage in a series of events or in a process of developmentThe project is only in the initial phase as yet, but it's looking quite promising.We're entering a new phase in international relations.If a child or young person goes through a period of strange or difficult behaviour, people sometimes describe it as a phase, meaning that it will stop after a while.When I was in my early teens I went through a phase of only ever wearing black.He started wearing women's clothes but I thought it was just a phase and he'd get over it soon.The phases of the moon are the regular changes in its shape as it appears to us on Earth.If two things are happening in/out of phase they are reaching the same or related stages at the same time/at different times.
Meaning of PHASE in English
Cambridge English vocab. Кембриджский английский словарь. 2012